1. Field of the Invention
One disclosed aspect of the embodiments relates to a vibrating apparatus, driving apparatus having the vibrating apparatus, and optical device. Particularly, one embodiment relates to an optical device such as a camera, facsimile, scanner, projector, photocopier, laser printer, inkjet printer, lens, binoculars, image display devices, and so forth. Also, one embodiment relates to an vibrating device used for a dust removal apparatus for such an optical device, and a driving device to drive a driven member by vibrating.
2. Description of the Related Art
In imaging apparatuses in recent years, resolution of optical sensors has improved markedly, and accordingly dust that adheres to the optical system during use has influenced imaged images.
In particular, resolution of imaging devices that are video cameras and still cameras has been significantly improving, whereby when dust adheres to the optical device that is disposed on the optical path near the imaging device, image defects may occur.
For example, when dust from the outside or abrasion powder generated from internal mechanical surfaces in sliding contact adheres to an infrared-cut filter, an optical low-pass filter, or the like, the image on the imaging device face has little blurring so the dust may show up in the imaged image.
On the other hand, imaging units such as copier, facsimile, scanner, or the like read a flat document by scanning a line sensor or by scanning a document that is placed near a line sensor.
When dust adheres to the light beam incident portion towards the line sensor, the dust may show up on the scanned image.
Also, with a method for so-called scan-reading where a document is read during transport from a device with a method to scan a document, a reading portion of a facsimile, or an automated document sending device of a photocopier, there are cases where one piece of dust may show up as a continuous line image in the document sending direction.
Thus, a problem occurs in that image quality is significantly lost.
Image quality may be recovered by wiping away the dust by hand, but the dust adhered during use has to be confirmed after photographing.
In the meantime, the image of dust shows up on the photographed or scanned image, so corrections have to be made by image processing with software, and a photocopier outputs the image to paper media at the same time so correction takes much work.
To address such problems, with the related art, a dust removal apparatus that moves dust from the image reading portion by applying vibrations, and optical devices having the dust removal apparatus installed therein have been proposed (see Japanese Patent Laid-Open No. 2008-207170).
FIG. 13A is a diagram illustrating a configuration of a vibration apparatus of a dust removal apparatus with the related art which is disclosed in Japanese Patent Laid-Open No. 2008-207170. A vibration apparatus 300 is provided to an imaging device 301 that converts the received subject image into electrical signals and creates image data. Space in front of the front face of the imaging device 301 is sealed off by the vibration apparatus 300 and imaging device 301. That is to say, the vibration apparatus 300 is joined to the front face side of the imaging device 301 so as to seal off the space via a sealing member or the like. The vibration apparatus 300 is made up of an optical device 302 having a rectangular plate shape and a pair of piezoelectric elements 303a and 303b which are electromechanical energy conversion devices that are fixed to both sides of the optical device 302 by an adhesive. An alternating voltage Va is applied to the piezoelectric element 303a as a driving voltage, and an alternating voltage Vb is applied to the piezoelectric element 303b as a driving voltage.
The label A in FIG. 13B indicates a displacement distribution of a primary out-of-plane bending vibration (standing wave), and the label B indicates a displacement distribution of a secondary out-of-plane bending vibration (standing wave). The vertical axis shows the direction of the imaging device 301 side to be negative, with a displacement of the out-of-plane direction of the front face on the opposite side from the side where the imaging device 301 of the vibration apparatus 300 is disposed. The horizontal axis corresponds to the position in the lengthwise direction of the vibration apparatus 300 as illustrated in the diagram. The alternating voltage Va and alternating voltage Vb together are a cyclic alternating voltage that has a response to the resonance phenomenon of the primary out-of-plane bending vibration and secondary out-of-plane bending vibration, and further the alternating voltage Va and alternating voltage Vb have difference temporal phases. Thus, a combined vibration, where the two vibrations of the primary out-of-plane bending vibration and secondary out-of-plane bending vibration having different temporal phases are synthesized, is excited in the vibration apparatus 300.
FIGS. 14 through 17 are graphs illustrating, for each time phase, the primary out-of-plane bending vibration and secondary out-of-plane bending vibration in the case that the two vibrations have temporal phase difference of 90° and an amplitude of 1:1, and the displacement and displacement speed of the vibrating bodies having these vibrations overlapping with each other. The vertical axis shows the displacement and displacement speed with the direction of the imaging device 301 side to be negative. The horizontal axis corresponds to the position in the lengthwise direction of the vibration apparatus 300, similar to FIG. 13B.
In the diagrams, waveform C indicates a displacement of the primary out-of-plane bending vibration. Waveform D indicates a displacement of the secondary out-of-plane bending vibration. Waveform E indicates displacement of the vibration apparatus 300 having the two vibrations overlapping with each other. Waveform G indicates displacement of the vibration apparatus 300 at a time phase 30° before the waveform E. Waveform F indicates displacement speed that has been normalized by the vibration apparatus 300. In the case that the dust removal apparatus is operated, the dust that is adhered to the surface of the optical device 302 is moved so as to be pulled by force of the normal direction of the surface of the optical device 302 when the optical device 302 pushes up the dust towards the out-of-plane direction (the positive direction of the vertical axis in FIGS. 14 through 17).
That is to say, in each time phase, when the value of the waveform F indicating displacement speed is positive, the dust is pushed up in the out-of-plane direction, receives force in the normal direction of the waveform E which indicates the displacement of the vibration apparatus 300 in the time phase therein, and the dust is moved. In the case that the displacement is provided while the optical device 302 is standing at a defined angle (typically, vertical), in the case that the dust adhered to the surface of the optical device 302 receives force in the normal direction of the surface of the optical device 302 and drawn, the dust does not adhere again, with a constant probability, and falls due to gravity.
The arrow h in FIGS. 14 through 17 illustrate the direction that the dust moves. In viewing FIGS. 14 through 17, from position 60 to 300 of the optical device 302, the amount of vibration to move the dust in the positive direction of the horizontal axis is relatively greater than the amount of vibration to move dust in the negative direction. Therefore, the dust may be moved in the positive direction of the horizontal axis. In the case that the effective portion of the optical device 302 as to the imaging device 301 (also called optical effective portion) is in the range of position 60 through position 300, the dust may be removed from the effective portion. Now, in the case that an optical device is disposed in the light path of the imaging device, the light entering the imaging device means the range which passes through the optical device.